Project Summary/Abstract To learn in a bustling classroom, children must effectively perceive speech in noise. Hearing in noise is a complicated task that relies upon factors such as attention, memory, and linguistic knowledge, in addition to precise auditory-neurophysiological processing of sound. Accumulating evidence suggests these mechanisms vary depending on the speech-in-noise task demands. For instance, when speech and noise are co-located, this demands a large cognitive load and recruits working memory, while spatially separating the speech and noise diminishes this load and draws on alternative skills. However, research has focused on the mechanisms underlying hearing in noise in isolation; no study to date has considered how they interact during critical developmental years. This proposal seeks to identify the relative contributions of neurophysiological, cognitive, and linguistic processes supporting speech-in-noise perception in young children. Neural, cognitive, and linguistic indices include those that have been shown to support speech-in-noise perception in children and adults, and their relative contributions and interactions will be evaluated under various masking conditions (i.e., co-located, spatially separated). The long-term goal is to understand the ingredients and obstacles to successful listening in young childhood, and the overall objective to identify the relative contributions and interactions of neurophysiological, cognitive, and linguistic factors supporting hearing in noise in early development. The central hypothesis is that speech-in-noise perception in early childhood is supported by dissociable neurophysiological, cognitive, and linguistic processes, and that the relative contributions of these processes depend on the degree of masking and the cognitive load of the task. One overarching experiment is proposed with the specific aim to determine the neurophysiological, cognitive, and linguistic mechanisms supporting speech-in-noise perception in young children (age 5-7) with respect to high masking (i.e., co- located), and low masking (i.e., spatial separation). Understanding the independent contributions and interactions of these mechanisms will have a positive translational impact by advancing early identification strategies and informing the development of targeted interventions that improve hearing in noise.